The following abbreviations and term are herewith defined, at least some of which are referred to within the following description of the present disclosure.
3GPP 3rd-Generation Partnership Project
APDU Application Protocol Data Unit
ASIC Application Specific Integrated Circuit
BSS Base Station Subsystem
BBSLAP Base Station Subsystem Location Services Assistance Protocol
BTS Base Transceiver Station
CN Core Network
DL Downlink
DSP Digital Signal Processor
EC Extended Coverage
EC-GSM Extended Coverage Global System for Mobile Communications
eNB Evolved Node B
EDGE Enhanced Data rates for GSM Evolution
EGPRS Enhanced General Packet Radio Service
GSM Global System for Mobile Communications
GERAN GSM/EDGE Radio Access Network
GPRS General Packet Radio Service
IE Information Element
IoT Internet of Things
LTE Long-Term Evolution
MME Mobility Management Entity
MPM Multilateration Positioning Method
MS Mobile Station
MTA Multilateration Timing Advance
MTC Machine Type Communications
NB-IoT Narrow Band Internet of Things
PACCH Packet Associated Control Channel
PDN Packet Data Network
PDU Protocol Data Unit
PLMN Public Land Mobile Network
PS Packet Switched
RAN Radio Access Network
RLC Radio Link Control
RRLP Radio Resource Location Services Protocol
SCCP Signalling Connection Control Part
SGSN Serving GPRS Support Node
SMLC Serving Mobile Location Center
TA Timing Advance
TBF Temporary Block Flow
TS Technical Specification
TSG Technical Specification Group
UE User Equipment
UL Uplink
WCDMA Wideband Code Division Multiple Access
WiMAX Worldwide Interoperability for Microwave Access
Extended Coverage: The general principle of extended coverage is that of using blind transmissions for the control channels and for the data channels to realize a target block error rate performance (BLER) for the channel of interest. In addition, for the data channels the use of blind transmissions assuming MCS-1 (i.e., the lowest modulation and coding scheme (MCS) supported in EGPRS today) is combined with HARQ retransmissions to realize the needed level of data transmission performance. Support for extended coverage is realized by defining different coverage classes. A different number of blind transmissions are associated with each of the coverage classes wherein extended coverage is associated with coverage classes for which multiple blind transmissions are needed (i.e., a single blind transmission is considered as the reference coverage). The number of total blind transmissions for a given coverage class can differ between different logical channels.
At the 3rd-Generation Partnership Project (3GPP) Technical Specification Group (TSG) Radio Access Network (RAN) Meeting #72, a Work Item on “Positioning Enhancements for GERAN” was approved (see RP-161260; Busan, Korea; 13-16 Jun. 2016—the contents of which are hereby incorporated herein by reference for all purposes), wherein one candidate method for realizing improved accuracy when determining the position of a mobile station (MS) is multilateration timing advance (MTA) (see RP-161034; Busan, Korea; 13-16 Jun. 2016—the contents of which are hereby incorporated herein by reference for all purposes), which relies on establishing the MS position based on Timing Advance (TA) values in multiple cells.
At the 3GPP TSG-RAN1 Meeting #86, a proposal based on a similar approach was made also to support positioning of Narrow Band Internet of Things (NB-IoT) mobiles (see R1-167426; entitled “On timing advance based multi-leg positioning for NB-IoT;” Source: Ericsson LM; Gothenburg, Sweden; 22-26 Aug. 2016—the contents of which are hereby incorporated herein by reference for all purposes). In regards to IoT devices, it expected that in a near future, the population of Cellular IoT devices will be very large. Various predictions exist; one such prediction is that there will be >60000 cellular IoT devices per square kilometer (see draft Change Request (CR) 43.059 entitled “Introduction of Multilateration”, Source Ericsson LM, RAN WG6 telco #1 on ePOS_GERAN, dated: Dec. 15, 2016—the contents of which are hereby incorporated herein by reference for all purposes), and another prediction is that there will be 1000000 cellular IoT devices per square kilometer (see R1-167426; entitled “On timing advance based multi-leg positioning for NB-IoT;” Source: Ericsson LM; Gothenburg, Sweden; 22-26 Aug. 2016—the contents of which are hereby incorporated herein by reference for all purposes). A large fraction of these cellular IoT devices are expected to be stationary, e.g., gas and electricity meters, vending machines, etc. . . . . Extended Coverage GSM-IoT (EC-GSM-IoT) and NB-IoT are two standards for Cellular IoT that have been specified by 3GPP TSG GERAN and TSG Radio Access Network (RAN).
Timing Advance (TA) is a measure of the propagation delay between a base transceiver station (BTS) and the MS, and since the speed by which radio waves travel is known, the distance between the BTS and the MS can be derived. Further, if the TA applicable to the MS is measured within multiple BTSs and the positions (i.e., longitude and latitude) of these BTSs are known, the position of the MS can be derived using the measured TA values. The measurement of the TA requires that the MS synchronize to each neighbor BTS and transmit a signal time-aligned with the timing of the BTS estimated by the MS. The BTS measures the time difference between its own time reference, and the timing of the received signal (transmitted by the MS). This time difference is equal to two times the propagation delay between the BTS and the MS (one propagation delay of the BTS's synchronization signal sent to the MS, plus one equal propagation delay of the signal transmitted by the MS back to the BTS).
As shown in FIG. 1 (PRIOR ART), once a set of TA values TA1, TA2, and TA3 are established using a set of one or more BTSs 1021, 1022, 1023 (only three shown) during a given positioning procedure, the position of the MS 104 can be derived through a so called Multilateration Timing Advance (MTA) procedure wherein the position of the MS 104 is determined by the intersection of a set of hyperbolic curves 1061, 1062, 1063 associated with each BTS 1021, 1022, 1023. The calculation of the position of the MS 104 is typically carried out by a serving positioning node 110 (e.g., serving Serving Mobile Location Center 110 (SMLC 110)), which implies that all of the derived TA values TA1, TA2, and TA3 and the associated position information of the BTSs 1021, 1022, 1023 needs to be sent to the serving positioning node 110 (i.e., the serving SMLC 110) which initiated the positioning procedure. In this example, the BTSs 1021, 1022, 1023 transmit their respective TA1, TA2, and TA3 to one BSS 108 which then transmits TA1, TA2, and TA3 to the SMLC 110. The BSS 108 and SMLC 110 are both connected to a SGSN 112. It should be appreciated that each BTS 1021, 1022, 1023 could also be connected to different BSSs (not shown) where in any configuration the SMLC 110 is still provided with the calculated TA1, TA2, and TA3.
At the 3GPP TSG-RANG Meeting #2 as well as at the first RANG teleconference on Positioning enhancements for GSM/EDGE Radio Access Network (GERAN), several draft Change Requests (CRs) to 3GPP TS 43.059 V13.2.0, dated Jun. 1, 2016 describing the Multilateration Timing Advance procedure were reviewed and discussed. For example, FIG. 2 (PRIOR ART) which illustrates the Multilateration Timing Advance procedure in the Packet Switched (PS) domain was discussed at this meeting and during the teleconference. In particular, FIG. 2 (PRIOR ART) was presented in the following CRs: (1) R6-160274, entitled “CR 43.059-0081 rev 3 Introduction of Multilateration,” Source: Ericsson LM, Reno, Nev., U.S.A., 14-18 Nov. 2016 (http://www.3gpp.org/ftp/tsg_ran/WG6_legacyRAN/TSGR6_02/Docs/R6-160274.zip); and (2) the draft CR 43.059 entitled “Introduction of Multilateration”, Source Ericsson LM, RAN WG6 telco #1 on ePOS_GERAN, dated: Dec. 15, 2016) (note: the contents of these documents are hereby incorporated herein by reference for all purposes). In the FIG. 2A's step 4, the sending of the Radio Resource Location services Protocol (RRLP) Multilateration Timing Advance Request message from the SMLC 110 to the MS 104 is tunneled via the BSS 108 and the SGSN 112, where this tunneling means that the type of positioning procedure to be used by the MS 104 which is being requested to perform the MTA procedure is transparent to the SGSN 112 (i.e., the SGSN 112 is aware that the MS 104 is being requested to perform a positioning procedure but not the specific MTA procedure). This transparent tunneling and the resulting lack of knowledge on the part of the SGSN 112 that the MS 104 is being requested to perform a MTA procedure leads to problems. A more detailed discussion about this transparent tunneling between the BSS 108 and the SGSN 112 and the problems associated with this transparent tunneling are described in more detail next.
FIG. 2A's step 4 comprises the following signaling: (1) the SMLC 110 transmits a BSSMAP Connection Oriented Message 202 (which includes a RRLP APDU 204 which includes a RRLP Multilateration Timing Advance (MTA) Request message 206 intended for the target MS 104) to the BSS 108 (see FIG. 2B's step 4a); (2) the BSS 108 transmits a BSS GPRS Protocol (BSSGP) POSITION-COMMAND PDU 208 (which includes the RRLP APDU 204 which includes the RRLP MTA Request message 206) to the SGSN 112 (see FIG. 2B's step 4b); (3) the SGSN 112 transmits a BSSGP Downlink (DL) UNITDATA PDU 210 which includes a LLC PDU 212 (which includes the RRLP APDU 204 which further includes the RRLP MTA Request message 206) to the BSS 108 (see FIG. 2B's step 4c); (4) the BSS 108 transmits the LLC PDU 212 (which includes the RRLP APDU 204 which further includes the RRLP MTA Request message 206) to the MS 104 (see FIG. 2B's step 4d); and (5) the MS 104 transmits a PACCH acknowledgment 214 to the BSS 108 (see FIG. 2B's step 4e). FIG. 3 (PRIOR ART) is a diagram that illustrates the content of the BSSGP POSITION-COMMAND PDU 208 per the standard 3GPP TS 48.018's TABLE 10.5.4 V14.1.0, dated Dec. 23, 2016—the contents of which are hereby incorporated herein by reference for all purposes. The BSSGP POSITION-COMMAND PDU 208 (which includes the RRLP APDU 204 which in this disclosure further includes the RRLP MTA Request message 206) allows the BSS 108 to request the SGSN 112 to perform the position command procedure (note: as discussed above the SGSN 112 is aware that the MS 104 is being requested to perform a position command procedure but does not know that the position command procedure is a MTA procedure). FIG. 4 (PRIOR ART) is a diagram that illustrates the content of the RRLP APDU 204 per the standard 3GPP TS 48.018's TABLE 11.3.49 V14.1.0, dated Dec. 23, 2016. The RRLP APDU 204 conveys an embedded message associated with a higher level protocol where in this case the embedded message is the RRLP MTA Request message 206. FIG. 5 (PRIOR ART) is a diagram that illustrates the content of RRLP Flags Information Element (IE) 500 (see also FIG. 3) per the standard 3GPP TS 48.018's TABLE 11.3.60 V_14.1.0, dated Dec. 23, 2016. The RRLP Flags IE 500 provides the control information for the RRLP APDU 204 where the fields are coded as follows: Flag 1 (Octet 3, bit 1) wherein bit value “0” indicates a position command (BSS 108 to SGSN 112) or final response (SGSN 112 to BSS 108); bit value “1” indicates that this is not a position command or final response; and spare where these bits are ignored by the receiver and set to zero by the sender.
The transparent tunneling of the RRLP MTA Request message 206 through the SGSN 112 entails where the SGSN 112 upon receiving the BSSGP POSITION-COMMAND PDU 208 is informed that the BSS 108 is requesting the SGSN 112 to perform a positioning procedure but the SGSN 112 does not know that the specific positioning procedure is a Multilateration Timing Advance (MTA) procedure. The SGSN 112 does not know that the positioning procedure is a Multilateration Timing Advance (MTA) procedure because the SGSN 112 does not read the RRLP APDU 204 which includes the RRLP MTA Request message 206 but instead the SGSN 112 just inserts the RRLP APDU 204 which includes the RRLP MTA Request message 206 within the LLC PDU 212 which is included in the BSSGP Downlink (DL) UNITDATA PDU 210 that the SGSN 112 then transmits to the BSS 108. The transparent tunneling of the RRLP MTA Request message 206 through the SGSN 112 leads to several problems when the target MS 104 has been requested unknowingly to the SGSN 112 to perform a Multilateration Timing Advance (MTA) procedure. These problems are as follows:
Problem 1: While a ready timer 420 is running in the SGSN 112 for a given MS 104, the SGSN 112 is not aware if the SMLC 110 has triggered (per FIG. 2B's step 4a) the MS 104 to perform the Multilateration Timing Advance procedure or not (note: in regards to the ready timer 420, it should be appreciated that if the MS 104 is in idle mode, then FIG. 2A's step 1 is preceded by the SGSN 112 sending a paging message to the MS 104, and when the SGSN 112 receives a paging response message from the MS 104, the SGSN 112 will start the ready timer 420 for the MS 104). This is a problem because if the MS 104 is performing the Multilateration Timing Advance procedure and this ready timer 420 is running, then the MS 104 is not reachable in the cell where the MS 104 last sent an uplink LLC PDU (e.g., the paging response message which started the ready timer 420) and the SGSN 112 that receives downlink data for the MS 104 will attempt unsuccessfully to deliver that downlink data to the MS 104. The MS 104 will not be available to receive the downlink data from the SGSN 112 during the Multilateration Timing Advance (MTA) procedure because the MS 104 per the MTA procedure has to successively connect to multiple neighboring cells for the purpose of allowing the BTS managing each of these cells to estimate the corresponding timing advance value (i.e., the MS 104 will be going from cell to cell while performing the MTA procedure and will therefore not be reachable on the control channel of the specific cell that the SGSN 112 associates with the MS 104 for which the ready timer 420 is running).Problem 2: While the ready timer 420 is not running for a given MS 104, the SGSN 112 is not aware if the MS 104 is still performing a previously triggered Multilateration Timing Advance procedure. This is a problem because if the MS 104 is currently performing the previously triggered MTA procedure and the ready timer 420 is not running, then this means that the MS 104 is not reachable in its current paging area and that the paging procedure should therefore not be triggered by the SGSN 112. That is, if the SGSN 112 does trigger the paging procedure while the MS 104 is currently performing the previously triggered MTA procedure then the associated paging message will not be received by the MS 104 because the MS 104 is not listening for pages while performing the MTA procedure (i.e., the MS 104 will be going from cell to cell while performing the MTA procedure and will therefore not be reachable on the control channels of the cells comprising the paging area that the SGSN 112 associates with the MS 104 for which the ready timer 420 is not running).
In view of the foregoing, it can be appreciated that there is a need to address the aforementioned problems associated with the transparent tunneling between the BSS 108 and the SGSN 112 when the target MS 104 is being requested to perform a Multilateration Timing Advance (MTA) procedure. These needs and other needs are addressed by the present disclosure.